The present invention relates to a method and apparatus for arranging or creating recipes for imaging with a critical-dimension scanning electron microscope (CD-SEM), wherein each of the recipes defines not only the coordinates of the addressing point (AP), focusing point (FP), stigmatic point (SP), brightness/contrast control point (BP), or end measuring point (EP) used to acquire images at any position on a sample with the CD-SEM, but also those image templates or imaging parameters (or the like) that are associated with the above coordinates. The invention is also concerned with a shape evaluation apparatus (SEM apparatus) for semiconductor patterns.
Traditionally, the CD-SEM is most commonly used as measuring apparatus to inspect by measuring the workmanship of the highly accurate wiring patterns formed on semiconductor wafers. In SEM apparatus such as the CD-SEM, dimensionally critical points on the semiconductor patterns that require inspection are observed as end measuring points through the SEM, then various dimensional data on the patterns, such as wiring widths, are measured from the images acquired during the observation process, and the dimensional data is monitored to detect changes in process parameters.
To perform these inspections, it is necessary to arrange the imaging recipes that define the coordinates of imaging points, imaging parameters, image templates of each imaging point, and other data.
Japanese Patent Laid-Open No. 2002-328015 is known as a publication that discloses a technique for arranging recipes for imaging with such a SEM apparatus.
Japanese Patent Laid-Open No. 2002-328015 describes a semiconductor inspection system constituted by two subsystems. One is a navigation system that stores design information of a semiconductor wafer such as CAD data or the like and sets the imaging/inspection parameters including the regions of the semiconductor wafer that are to be inspected, based on the stored design information. The other is a scanning electron microscopic system that acquires images of the semiconductor wafer in accordance with the set imaging/inspection parameters and inspects the wafer. According to Japanese Patent Laid-Open No. 2002-328015, this semiconductor inspection system also has a function that detects the position of an addressing point (AP) from the CAD data and registers the CAD data of this detected position as a template. In addition, this system has a function that acquires a SEM image at the AP, then matching processes between the acquired SEM image and the registered CAD template at the AP, and re-registers a SEM image corresponding to the position of the CAD template as an another template, thereafter to use the re-registered SEM template subsequently.
For the semiconductor inspection system of described in Japanese Patent Laid-Open No. 2002-328015, however, the linear image created from the CAD data (for example, an image on which only the boundary of a mask for a resist is delineated as edges) is used to determine imaging points manually or automatically. Therefore, there has been the problem that appropriate imaging points cannot be selected because unbridgeable gulf of externals between the above linear image and an actual SEM image is large.
(1) Also, since the arrangement of an imaging recipe requires operator's knowledge such as what kind of pattern is to be selected as an AP to succeed in addressing, how to define the above knowledge as process rules in the system becomes important during automatic recipe arrangement.
(2) In addition, the above-mentioned imaging recipe is not of such a nature that it needs only to be arranged one time, and the AP, FP, SP, BP, or EP to be set is likely to change according to the subject of imaging (namely, the particular differences in process rule or manufacturing process) or the imaging parameters to be used, or other factors. Accordingly, it becomes important how to update the imaging recipe in rapid response to such changes in the imaging subject or in the imaging conditions.
(3) Furthermore, after constructing the system for implementing such automatic recipe arrangement as mentioned above, it becomes important how to judge the appropriateness of the imaging recipe that has been generated per arbitrary selection rules in the above system, or how to judge the appropriateness of the selection rules. Besides, it becomes important how to perform corrections if the imaging recipe or the selection rules are judged to be inappropriate.